(a) Field of the Invention
The present invention relates to an observation apparatus, and in particular to an apparatus for observing the blood circulating function of a patient with no contact with the blood by observing the waveform of the arterial pulses.
(b) Prior Art
Cardiographic or ultrasonic tomographic diagnosis apparatus has heretofore been used for examination of the heart disease.
Since the arterial pulses related with the motion of the heart contain important information representative of the condition of the blood circulating function, they are widely used for determining whether or not the blood circulating function is good. Observation of the volumetric pulses representative of the content of blood in the capillary vessels has generally been conducted.
A method of converting changes in pressure due to the heart beat into electrical signals by using a piezo-electric element or capacitor microphone or a method for optically detecting changes in the amount of blood flow by using optical modulating action of hemoglobin in blood have been adopted for detecting the arterial pulses.
In Oriental medicine, the conditions of a patient are determined by sphygmic diagnosis solely relying on the sense of touch of the arterial pulses on the "sunko", that is, the processus styloideus radii on the inner side of the wrist. In the sphygmic diagnosis of Oriental medicine, the pulses on the "sunko" are classified into those on three spots, such as upper, middle and lower spots which are referred to as "shun", "khan" and "shaku", respectively and two kinds of pulsation condition "myakki" on the pulse route "keimyaku" appeared on respective spots are sensed.
The term "shun" means the heart side of the artery of the wrist. The pulses on the "shun" represent the health conditions of the patient from the head to the chest. The term "khan" means the middle artery of the wrist between the distal end and the heart. The pulses on the "khan" represents the health conditions between the chest and the navel. The term "shaku" means the distal end side of the artery in the wrist and the pulses on the "shaku" represents the health conditions between the navel and the toe.
A sphygmic diagnosis apparatus in which arterial pulses are detected from the artery of a human being by means of sensors such as an infrared ray sensor or a pressure sensor for performing the diagnosis by observation of the sphygmogram has heretofore been known as is disclosed in the specification of the Japanese Examined Patent Publication No. 57-52054.
The disclosed diagnosis apparatus comprises three pressure sensor 51, 52 and 53 for converting the arterial pulses on the three spots such as "shun", "khan" and "shaku" of the "sunko" into electrical signal waves and a cuff band 55 which is mounted on the wrist 54 of a patient for biasing the pressure sensors 51, 52 and 53 upon the artery of the wrist as shown in FIG. 1.
The pressure sensors 51, 52 and 53 are disposed on the wrist 54, that is, on and along the artery in the "sunko" and the cuff 55 is wrapped around the wrist. A compressed air is pumped into an air bag (not shown) provided on the cuff 55 from a pneumatic pump via a conduit 56. The arterial pulses can be measured by adjusting the amount of the pumped air to change the pressure applied upon the artery.
The pressure sensors 51, 52 and 53 comprise, for example, so-called electrostatic microphones or piezoelectric microphones. Specifically, in case of the electrostatic microphone, a high d.c. voltage is applied across an electrode of a vibrating plate and a fixed electrode of the vibrating plate is brought into direct contact with a spot on which a pressure is detected, for example the artery of the "sunko". The spacing between the electrode of the vibrating plate and the fixed electrode is changed due to pressure to change the electrostatic capacity therebetween. The voltage generated at this time is detected. The pressure sensors 51, 52 and 53 are connected with an electromagnetic oscillograph and the like through connection codes 51a, 52a and 53a respectively so that the measured arterial pulses are recorded on a recording paper and the like for observing the sphygmogram.
Although the cardiography or ultrasonic tomography has been used for examination of heart disease as mentioned above, it is very hard to quantitatively diagnose the condition of the heart disease by observing the condition of the blood circulating function with no contact with the blood. Confirmation of an abnormality has been visually carried out by well experienced medical doctors.
There has been no means for measuring the viscosity of the blood in the artery which is changed by the disease of the internal organs such as heart disease or liver disease except for the blood circulating function for examining the heart disease. Information on the viscosity of blood can not be used for diagnosis of the disease of the internal organs.
It is hard to observe the hardness of the artery, which changes with an advance in the heart disease, with no contact with the blood. A method of estimating the hardness of the artery by pressing a sensor for investigating the relation between stress and strain upon the radial artery has been known as a method of measuring the hardness of the artery without contacting blood. However, this method is strongly influenced by the tissue between the artery and the upper skin. Accordingly, this method is inaccurate so that the hardness of the artery can not be quantified.